(a) Field of the Invention
The present invention relates to a wet image-forming apparatus, and in particular, to a wet image-forming apparatus employing a liquid developer used in an electrophotographic printer.
(b) Description of the Related Art
A conventional wet image-forming apparatus shown in FIG. 1 includes a developing roller 11 which rotates in a direction shown by an arrow xe2x80x9cbxe2x80x9d for developing electrostatic latent images formed on a photoreceptor B, a developing blade 12 for removing toner particles on the developing roller 11, a brush roller 13a for removing the toner particles from the developing blade 12, a manifold 14 for supplying a liquid developer to the developing roller 11, a reservoir 15a for storing the liquid developer in order to dip the brush roller 13a in the liquid developer during printing, a shield 17 for controlling the flow of the liquid developer, a squeezing roller 18 for removing the excessive developer on the photoreceptor B during the printing and for cleaning the photoreceptor B immediately before the stopping of the apparatus, a wiping blade 19 which is pressed against the squeezing roller 18 during the cleaning of the photoreceptor B, a squeezing support 20 which supports the squeezing roller 18 and the wiping blade 19 and shifts the vertical positions thereof with respect to the developing roller 11, and a developing support 21 for supporting the developing roller 11, the manifold 14, the reservoir 15a and the other elements.
Because of a difference between the electrified potential of the photoreceptor B and the developing potential VD applied to the developing roller 11, an electric field which is reverse to that of the exposed portion of the photoreceptor B is generated on the non-exposed portion of the photoreceptor B during the printing. The electric field causes the toner particles to adhere to the developing roller 11 in a reverse image developing process. The apparatus of FIG. 1 has a disadvantage in that it is difficult to keep a developing gap constant, and also in that the developing roller 11 requires cleaning. For cleaning purposes, the developing blade 12 is pressed against the outer peripheral surface of the developing roller 11 to remove the toner particles, while the toner particles adhering to the developing blade 12 are removed with the brush roller 13a. The brush roller 13a is manufactured by incorporating synthetic insulating resin fibers, such as rayon and nylon, on a cylindrical member. The reservoir 15a is also made of an insulating material.
As described above, the toner particles adhering to the developing blade 12 are removed with the brush roller 13a. Accordingly, the toner particles are gradually accumulated on the brush roller 13a. 
When the accumulation of toner particles becomes excessive, the brushing roller 13a can no longer remove the toner particles adhering to the developing blade 12. The developing roller 11 under these conditions cannot be sufficiently cleaned.
If the liquid developer in the reservoir 15a is depleted upon the completion of printing, the toner particles adhering to the brush roller 13a are dried and coagulated, causing an increase in torque when the brush roller 13a is rotated. The dried and coagulated toner particles can cause damage to the developing blade 12 in the next printing.
In view of the foregoing, an object of the present invention is to provide a wet image-forming apparatus which prevents toner particles contained in a liquid developer from accumulating on a brush roller to overcome the above problems in the conventional art.
The present invention provides a wet image-forming apparatus including: a developing roller which rotates in a first direction for developing electrostatic latent images formed on a photoreceptor with a liquid developer; a developing blade disposed in contact with a surface of the developing roller for removing toner particles adhering to the surface of the developing roller after developing; a brush roller which rotates in the first direction for removing the toner particles from the developing blade; and a reservoir which stores the liquid developer for accommodating both of the developing blade and the brush roller to dip both in the liquid developer, wherein the developing roller, the brush roller and the reservoir are applied with a common developing voltage.
In accordance with the wet image-forming apparatus of the present invention, toner particles that adhere to the developing blade can be mechanically and electrically prevented from accumulating. Cleaning of the developing roller can be accomplished effectively because substantially the same voltages as the developing voltage are applied to the brush roller and the reservoir.
The above and other objects, features and advantages of the present invention will be more apparent from the following description.